High-resolution computed tomography and diffuse lung disease.

Diffuse lung diseases are often difficult to characterize on chest radiographs. It has been a challenge for the radiologist to obtain useful diagnostic information from these studies and then communicate that information to the clinician. Robert Heitzman recognized the utility of understanding lung diseases in terms of their effect on the structures of the secondary lobule. Unfortunately, he needed inflated lung specimens to reliably visualize the small structures within the secondary lobule. Such specimens are no longer needed. High-resolution computed tomography (HRCT) scans of the lung provide an excellent representation of the secondary lobule. In this monograph, we have attempted to explain the normal anatomy of the secondary lobule, the patterns of abnormality, the technique for performing HRCT, and an approach to diffuse lung disease. In the second half of the article we have classified the more common diffuse lung diseases according to the dominant pathologic change: high versus low attenuation.